Research suggests that gifted students benefit when their classroom teachers hold distinct dispositions regarding giftedness. However, most general education teachers have had little exposure to targeted dispositional development related to gifted learners, meaning their dispositions may be influenced by many different factors. In this phenomenological qualitative study, we interviewed eight teachers from diverse state and district contexts to (a) understand in-service teachers' commonly held dispositions regarding giftedness and (b) locate the ecological systems and interactions that inform the development of their dispositions. We found that interviewed teachers held mostly hindering beliefs and commitments in relation to gifted students. Their dispositions were most informed by their immediate environments (i.e., the microsystem, mesosystem, and exosystem), suggesting interventions targeted at those systems (e.g., articulated training on advanced pedagogies and social-emotional needs, access to gifted specialists and premade advanced learning materials, and changes to accountability incentives) can support more supportive dispositions toward gifted students.